Gun-stock riser for AR15 type tactical firearm

ABSTRACT

A cheek riser mechanism has a mounting base or saddle that is adapted for mounting to a gun-stock and defines guide rail members. A movable cheek riser member has guide grooves that receive the guide rail members and is linearly movable along the length of the guide rails. Upon rearward movement of the charging handle of an AR15 type rifle the movable cheek riser can be engaged and moved rearwardly by the user&#39;s hand or by the charging handle so that it does not interfere with a cartridge charging operation. A riser spring is compressed during rearward movement of the cheek riser and returns the movable cheek riser to its use position upon release of the charging handle.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to shoulder fired firearms, particularly tactical firearms having gun-stock mechanisms that have adjustable length for efficiency of storage and handling and for adjustment of the firearms to suit the intended usage, needs and the anatomy of different users. More particularly, the present invention concerns the presence of cheek riser devices on gun-stocks to provide users with more efficient and secure aiming of the firearm. Even more specifically, the present invention is directed to a tactical gun-stock cheek riser mechanism that has a movable riser component to prevent riser interference with the charging handle movement of the adjustable length gun-stock of an AR15 type tactical firearm.

2. Description of the Prior Art

Tactical firearms have been use for a considerable period of time that incorporate gun-stock mechanisms that provide for adjustment of gun-stock length as desired between a minimum length and a maximum length. The shoulder engaging adjustable gun-stock mechanisms permit length adjustment to enable users of different anatomy to adjust the firearm to a length that is comfortable for that individual. The gun-stock mechanism can be adjusted to its minimum length when the rifle is to be used in close quarters, such as in the rooms of a building or in a wooded area where brush or trees might interfere with efficient use of the rifle. When tactical firearms are to be stored the user can adjust the length of the gun-stock to or near its minimum length so that the length of the rifle will facilitate efficient storage. This adjustable length feature also facilitates ease of transportation of tactical firearms in vehicles or in other modes of transportation.

AR15 type tactical rifles have a receiver structure within which a bolt member is movable rearwardly to eject the cartridge case of a spent or fired round of ammunition from the cartridge chamber of the rifle barrel and is movable forwardly by the energy of a bolt return spring to pick up another cartridge from a cartridge magazine of the rifle and propel it into the cartridge chamber of the rifle barrel. When no cartridge is present within the rifle barrel, the user of the rifle will manually engage or grasp a charging handle that is present at the rear portion of the rifle receiver and move it rearwardly. A bolt actuating shaft extends from the charging handle into the receiver and has connection with the bolt of the firing mechanism so that rearward movement of the charging handle also causes rearward movement of the bolt to its charging position and compresses the bolt return spring. When the charging handle is released the force of the bolt return spring will drive the bolt member forward, causing the bolt to pick up a cartridge from the cartridge magazine, propel the cartridge into the cartridge chamber of the rifle barrel and temporarily lock the bolt against rearward movement by the force of cartridge chamber pressure when the cartridge is fired. In the event something should interfere with complete rearward movement of the charging handle, the bolt will not be moved rearwardly sufficiently to adequately compress the bolt return spring. When this condition occurs and the charging handle is released it is likely that the forwardly moving bolt will have insufficient force to pick up a cartridge and feed it into the cartridge chamber and achieve locking actuation of the bolt.

It has been determined that the presence of cheek projections on the gun-stocks virtually all types of shoulder fired firearms often enable users to aim the firearm more accurately since the cheek projections, also known as “cheek risers” permit the user to comfortably rest the cheek of the user's face on the cheek riser and position the user's aiming eye in substantial alignment with the center of telescopes and other sighting and aiming devices that are mounted to the firearm. Cheek risers are especially advantageous when elevated sighting devices such as telescopes or laser sights are employed. These cheek risers may be defined by the structure of the gun-stock of the firearm or may be in the form of attachments that are mounted to the gun-stock.

In the case of tactical rifles of the AR15 type, the rifles typically have gun-stocks of adjustable length as mentioned above. When a cheek riser is present on an adjustable length gun-stock, depending on the adjusted position of the gun-stock, the cheek riser can interfere with manual rearward movement of the charging handle of the firearm to its cartridge charging position. This condition also causes the bolt to fail to reach its cartridge charging position and fails to completely load or compress the bolt return spring. Upon release of the charging handle the bolt return spring can fail to move the bolt forwardly with sufficient force to pick up a cartridge from the cartridge magazine and propel it into the cartridge chamber and can fail to completely lock the bolt in preparation for firing of the cartridge. This cartridge feeding malfunction often results in the cartridge being only partially stripped from the cartridge magazine or becoming misaligned in the receiver so that cartridge jamming occurs. The jammed cartridge must be cleared from the receiver and a new cartridge must be charged into the firing chamber of the barrel before the firearm can be fired. During tactical situations time is often of the essence and the user of the firearm could be subject to serious danger during the time sequence that is required for clearing a jammed cartridge and again charging the rifle from the cartridge magazine by manual operation of the charging handle. It is desirable, therefore to provide a cheek riser device or mechanism that also has a characteristic of movement that accommodates and does not interfere with the rearward movement of the charging handle of a rifle regardless of the condition of the adjustable length gun-stock.

SUMMARY OF THE INVENTION

It is a principal feature of the present invention to provide a novel cheek riser device for AR15 type tactical rifles which is easily movable during rearward movement of the charging handle of the firearm so that the cheek riser device does not impede rearward movement of the charging handle and thus permits normal spring urged forward bolt movement as a cartridge is charged into the cartridge chamber of the barrel of the firearm.

It is another feature of the present invention to provide a novel movable cheek riser for attachment to the gun-stock of a tactical rifle and having the capability for accommodating adjustment of the length of the gun-stock of the firearm and yet maintaining efficient cheek riser positioning at all adjusted lengths of the firearm gun-stock between its minimum length and its maximum length, without cheek riser interference with the cartridge charging operation of the firearm.

It is another feature of the present invention to provide a novel cheek riser mechanism having a first cheek riser part that is attached in fixed relation to the gun-stock of a shoulder fired firearm and having a second cheek riser part that has reciprocating movement relative to the first cheek riser part and is easily movable to prevent cheek riser interference with manually actuated cartridge charging.

It is an even further feature of the present invention to provide a gun-stock that incorporates a novel movable cheek riser mechanism wherein the gun-stock defines a guide and retention system having a cheek riser member movably mounted thereto and being movable in response to manually actuated movement of the charging handle of the firearm.

Briefly, the various objects and features of the present invention are realized through the provision of a cheek riser assembly that has a mounting base or saddle structure that is adapted for mounting to an adjustable gun-stock by means of mounting screws or other mounting devices. The mounting base or saddle is intended for substantially fixed relation with the gun-stock structure. The mounting base or saddle structure defines spaced forwardly extending cheek riser guide members that permit the upper curved portion of the gun-stock to b exposed and ensures that the charging handle of the firearm will not contact any portion of the mounting base or saddle structure during charging handle movement. The mounting base or saddle structure defines opposed elongate first guide members that are disposed in substantially parallel relation with one another. A cheek riser member is movably mounted to the mounting base or saddle structure by second guide members that are engaged with the first guide members. One or more riser springs continuously urge the cheek riser member forwardly to a use position against the force of the riser springs. The force of the riser springs is overcome by manually applied rearward movement of the charging handle of the firearm, this preventing interference of the riser member with the rearward movement of the charging handle and ensuring complete spring urged forward cartridge charging movement of the bolt of the firearm for efficiency of cartridge charging and minimizing cartridge jamming during manually actuated charging of a cartridge from the cartridge magazine into the firing chamber of the firearm barrel. Movement of the cheek riser member may be linear movement or any other character of movement that permits movement of the cheek riser member in response to charging handle movement of the firearm.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features, advantages and objects of the present invention are attained and can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the preferred embodiment thereof which is illustrated in the appended drawings, which drawings are incorporated as a part hereof.

It is to be noted however, that the appended drawings illustrate only a typical embodiment of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.

IN THE DRAWINGS

FIG. 1 is a side elevation view showing a rear portion of a tactical firearm having a gun-stock of adjustable length and having a movable cheek riser mechanism embodying the principles of the present invention being in assembly with the gun-stock and further showing the charging handle of the firearm mechanism being pulled rearwardly during a manually actuated charging stroke by with the hand of a user and being in contact a movable slide member of the movable cheek riser mechanism;

FIG. 2 is an elevation view similar to FIG. 1, showing the movable cheek riser slide member being further moved rearwardly as the rearward charging movement of the charging handle continues;

FIG. 3 is an elevation view similar to FIGS. 1 and 2, showing the position of the movable cheek riser slide member when the charging handle of the firearm has been moved to the full extent of its rearward movement during manually actuated cartridge charging of the firearm mechanism;

FIG. 4 is an isometric illustration showing the cheek riser mechanism of the present invention with the movable cheek riser slide member being shown at its forward most or normal position;

FIG. 5 is a bottom view of the movable cheek riser mechanism of FIG. 4;

FIG. 6 is an isometric illustration showing the bottom and side details of the movable cheek riser mechanism of FIGS. 4 and 5;

FIG. 7 is a front view of the cheek riser mechanism of FIGS. 4-6;

FIG. 8 is a rear view of the movable cheek riser mechanism of FIGS. 4-6;

FIG. 9 is a plan view of the riser base or saddle structure of the cheek riser mechanism of the present invention being shown mounted in substantially fixed relation to a gun-stock and showing a pair of spaced guide members for guiding engagement within guide slots of a movable cheek riser slide member and slide stop members for guiding and limiting reciprocating movement of the cheek riser slide member; and

FIG. 10 is a bottom view of the cheek riser slide member of the movable cheek riser mechanism of the present invention, showing internal parallel guide grooves for slide control and for limiting cheek riser slide movement.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

Referring now to the drawings and first to FIG. 1, the rear portion of a shoulder fired AR15 type rifle is shown generally at 10 and has a receiver 12 from which projects a handgrip 14. A cartridge charging handle 15 of the rifle receiver is shown being moved from its retracted position by the fingers of a user's hand engaging the charging handle 15 and applying a pulling force. This pulling force moves the charging handle 15 and the bolt mechanism within the receiver rearwardly against the resistance of a bolt return spring that is located within the buffer tube of the firearm. In the charging handle position shown in FIG. 1 it should be noted that the rear portion of the charging handle is in contact with a cheek riser slide member which is discussed in greater detail below.

The charging handle 15 is mounted to a charging shaft 17 that extends into the receiver 12 and is connected with a bolt mechanism that is movable within the receiver of the firearm during cartridge charging and cartridge firing sequences. The charging handle 15 is manually movable rearwardly against the force of a bolt return spring and moves the bolt mechanism of the firearm rearwardly in preparation for charging the cartridge chamber of the firearm barrel with a cartridge. When the manual force on the charging handle 15 is released the bolt and the charging handle are propelled forwardly by the force of the bolt return spring. During this spring urged forward movement of the bolt mechanism, the bolt will pick up a cartridge from the cartridge magazine of the firearm and move it forwardly into the cartridge chamber of the barrel. The bolt mechanism will be locked at its fully forward or closed position, thereby securing and sealing a cartridge within the cartridge chamber and causing the bolt mechanism to remain closed and to resist rearward movement by the gas pressure that is developed upon firing of the cartridge within the cartridge chamber. The bolt mechanism is unlocked and moved rearwardly toward its full open position by cartridge gas pressure when the bullet being propelled through the rifle barrel passes a gas port and exposes the gas port to cartridge gas pressure. Cartridge gas pressure from the gas port of the firearm barrel acts on a piston rod member causing the piston rod to be moved rearwardly and apply a bolt unlocking force to the bolt mechanism. The piston rod force also moves the bolt mechanism rearwardly to eject the spent cartridge and repeat the cartridge charging process.

In the similar elevation view of FIG. 2 the charging operational sequence is shown in further progress, with the cartridge charging handle 15 of the rifle receiver having been pulled further rearwardly by the fingers of the user's hand, such that the cheek riser slide member is also being moved further rearwardly by the manual force being applied to the charging handle. A slide return spring of the cheek riser slide mechanism is being loaded during this rearward slide movement so that when the manual force on the charging handle is released the cheek riser slide member will be moved forwardly by the force of a slide return spring toward its original position.

The elevation view of FIG. 3 illustrates a further portion of the manually actuated operational sequence for charging a cartridge into the cartridge chamber of the firearm barrel. The Figure shows the charging handle 15 of the firearm being manually pulled substantially to its rearmost position and ready to be released for spring urged forward movement by the bolt return spring. The Figure also shows the cheek riser slide member having been moved by the charging handle substantially to its rearmost position. When the charging handle is released from the pulling force the bolt return spring will move the charging handle forwardly to its retracted position as the bolt return spring moves the bolt through the cartridge charging portion of its cartridge charging cycle. As the charging handle is moved forwardly the slide return spring of the cheek riser mechanism will move the cheek riser slide member forwardly to its operational position. This feature permits the firearm to be provided with a cheek riser to facilitate efficiency of firearm aiming and also ensures that the cheek riser is movable during manually actuated cartridge charging cycling and does not interfere with the cartridge charging cycle of the firearm. During a firing sequence the lost-motion connection of the charging handle with the bolt mechanism ensures that the charging handle remains at its forward most or retracted position.

The receiver 12 of the firearm 10 defines a gun-stock mount 16 that receives the externally threaded end 18 of a tubular gun-stock support member 20 that is also referred to as a buffer tube. Typically the buffer tube contains a bolt return spring and a spring follower, with the bolt return spring urging the spring follower in the forward direction toward the barrel of the firearm. When a cartridge is fired a cartridge gas energized bolt actuating rod member is moved rearwardly by cartridge gas pressure to unlock the bolt member and move it rearwardly against the resistance of the bolt return spring. This bolt recoil movement causes the bolt mechanism to move the spring follower rearwardly and accomplishes loading of the bolt return spring of the buffer tube. When rearward movement of the bolt mechanism has been overcome by the resistance of the bolt return compression spring the spring will drive the bolt mechanism forwardly to pick up a cartridge from a cartridge magazine of the receiver 12 and move the cartridge into the cartridge chamber of the firearm barrel. A lock plate 22 and lock nut 24 secure the buffer tube member 20 to the receiver 12 and permit the gun-stock to be easily removed from the receiver 12 and replaced if desired.

A moveable gun-stock 26, for engagement with the shoulder of a user, defines an internal receptacle within which is adjustably received the rear end portion of the tubular gun-stock member or buffer tube 20. The buffer tube 20 further defines an internal guide slot within which is received an elongate guide portion of the tubular gun-stock member 20, thus preventing rotation of the gun-stock relative to the buffer tube and permitting forward and rearward adjustment of the gun-stock member 26 relative to the buffer tube 20 to lengthen or shorten the firearm as suits the needs and desires of the user. Obviously, when the gun-stock member 26 is adjusted to its maximum length, a cheek riser member, if present on the gun-stock, will typically be located beyond the rearward stroke of the charging handle and will not interfere with the charging cycle of the firearm. However, if a cheek riser is present on the gun-stock then its presence could prevent the gun-stock from being adjusted to its minimum or intermediate length. Thus the presence of a cheek riser on a gun-stock could constitute a distinct disadvantage concerning normal use of the firearm.

A pivotally mounted latch member 32 is manually positioned to a latched position to secure the gun-stock member 26 at any desired position along the length of the tubular gun-stock member 20 between minimum and maximum length positions. A pivotally mounted latch release member 34 is mounted to the moveable gun-stock member 26 and upon manual movement about its pivot 36 causes latch releasing movement of a latch release pin 38 which in turn causes latch releasing movement of the latch member 32. This latch releasing movement frees the gun-stock member 26 for linear gun-stock position adjusting movement along the length of the tubular gun-stock member 20.

As mentioned above, it is often desirable to include a cheek riser on the gun-stock of a firearm to aid the user in positioning the user's eye for efficient aiming, especially if the firearm is fitted with an elevated sighting device such as a telescope. The movable cheek riser mechanism of the present invention can be provided in the form of an assembly that is mounted to a standard gun-stock or may be provided as a component or structure of a gun-stock. If a conventional cheek riser is present on the gun-stock of an AR15 type firearm the riser will typically interfere with manual rearward movement of the charging handle 15, especially if the gun-stock has been adjusted to its more collapsed position for minimum stock length as shown in FIG. 1. This interference can prevent the bolt of the firearm from being moved rearwardly to its full extent for maximum compression of the bolt return spring and thus can prevent the bolt from being cycled forwardly with sufficient spring induced force to pick up a cartridge from the cartridge magazine and charge the cartridge into the firing chamber of the firearm barrel. It is desirable, therefore, to provide an AR15 type firearm with a gun-stock having cheek riser assembly that incorporates a movable cheek riser member that is easily movable during charging handle manipulation so that the charging handle can be cycled to its full extent and the movable cheek riser will not interfere with the cartridge charging operation. This feature also permits the movable cheek riser to be returned to its cheek supporting position by spring force when the charging handle has been released by the firearm user and has been moved forwardly by the bolt return spring.

Referring now to FIGS. 1-6, 9 and 10 a cheek riser assembly having a variable position capability is shown generally at 40 and comprises a riser saddle structure 42 having a rear portion of generally U-shaped cross sectional configuration that defines a downwardly facing recess 43 that substantially fits the curvature of the upper curved surface portion 44 of the gun-stock 26. The riser base or saddle structure 42 is preferably composed of any of a wide range of polymer materials but may be composed of a metal such as steel, aluminum alloy or magnesium if desired. A pair of spaced cheek riser guide members 46 and 48 are integral with the riser base or saddle structure 42 and project forwardly from the U-shaped portion of the base or saddle structure 42. The spaced cheek riser guide members 46 and 48 each define externally projecting elongate guide rail members 50 and 52. The spacing of the cheek riser guide members 46 and 48 permits the curved upper portion 44 of the gun-stock 26 to be exposed so that the charging handle 15 of the firearm will not come into contact with any portion of the riser saddle structure 42 during its reciprocating charging movement. Thus it is possible for the charging handle 15 to actually come into contact with the upper curved surface 44 of the gun-stock without contacting any portion of the U-shaped saddle structure 42. The U-shaped portion of the saddle structure 42 also defines a pair of spaced guide and stop projections 54 and 56, shown in FIG. 9 that are disposed in generally parallel relation with one another and project upwardly and laterally from the U-shaped saddle structure. A plurality of saddle mounting tabs 58, 60, 62 and 64 extend downwardly from opposed edge portions 66 and 68 of the riser saddle structure 42 and each define mounting holes 70 that receive mounting screws 72 or any other suitable retainer devices that extend into the structural material of the movable gun-stock member 26.

As shown in FIGS. 9 and 10 a movable cheek riser member or slide 74 is received for linear reciprocating movement by the riser saddle structure 42 and defines spaced elongate internal guide slots 76 and 78 that receive the spaced guide and stop projections 54 and 56 of the U-shaped saddle structure. The internal guide slots 76 and 78 have closed ends that terminate short of the respective ends of the movable cheek riser member as shown in FIG. 10. The closed ends of the internal guide slots define stops that can be contacted by the respective ends of the spaced stop projections 54 and 56 to limit the length of the reciprocating movement of the movable riser member. Interrelation of the spaced stop projections 54 and 56 and the internal guide slots 76 and 78 also permit the normal position of the forward end of the movable cheek riser slide member to be substantially even with the forward end of the gun-stock 26 as is essentially shown in FIG. 1. These guide features permit the cheek riser member 74 to be linearly movable relative to the cheek riser saddle structure 42, the length of linear movement being greater than the manually energized rearward linear extension movement of the charging handle 15 of an AR15 type tactical firearm or its military equivalent.

As shown in FIGS. 5 and 6, the rearward end portion of the movable cheek riser member 74 can incorporate internal generally U-shaped structural ribs 76, 78, 80 and 82 that enhance the structural integrity of the cheek riser saddle structure 42. These U-shaped internal structural ribs establish contact with the upper curved surface 44 of the movable gun-stock 26 when the saddle structure 42 of the cheek riser assembly 40 is mounted in fixed relation with the movable gun-stock 26.

As shown in FIG. 5 and FIG. 10, the cheek riser saddle structure 42 also defines an elongate structural section 84 of generally cylindrical configuration which is also integral with the cheek riser saddle structure 42. This elongate cylindrical structural section defines a through passage 86 within which extends a plunger member 88 and a plunger spring 90 that is preferably in the form of a helical compression spring. A plunger support plate member 92 to which the plunger member 88 is fixed is mounted within a recess 94 that is defined within a front end wall 96 of the cheek riser slide member 74 by mounting screws 97 or other suitable fastener devices that extend through fastener openings 98 and are threaded into or otherwise engage within openings of the plunger support plate 92. If desired the support plate structure at the fastener openings may be internally threaded to receive the threads of the mounting screws 97. Also if desired the support plate may be mounted to the front end wall 96 by means of screw, nut and lock washer assemblies or by any other suitable means for attachment or mounting.

The front end wall 96 of the movable cheek riser member or slide 74 defines guide slots or notches 100 and 102 within which the externally projecting elongate guide members 50 and 52 are movably received. As the movable cheek riser or slide member 74 is moved linearly in the rearward direction by the charging handle of the firearm or by manual force applied by the user of the firearm the front end portion of the movable cheek riser or slide member will be guided and will be prevented from separating from the fixed cheek riser saddle structure 42.

As the riser slide member 74 is moved rearwardly by the charging handle 15 of the firearm or by manually applied force the plunger member 88, being mounted to the forward wall structure 96 of the riser slide member, will be moved within the through passage 86 of the elongate structural section 84 of the riser base or saddle structure 42. As this occurs the compression spring 90 will be further compressed so that a return spring force exists that urges the riser slide member toward its original operational position. Thus, during normal charging operations for the firearm the charging handle is pulled to its maximum extent and released. As the charging handle is pulled it engages and causes movement of the riser slide member 74 so that the riser slide member does not interfere with complete and efficient charging handle movement. When the charging handle is released by the firearm user the bolt return spring will move the charging handle forwardly to its original position, in the process causing charging of a cartridge into the cartridge chamber of the firearm. During forward movement of the charging handle the spring force on the riser slide member will move the riser slide member forwardly, essentially following the charging handle. When the charging handle 15 has become seated the riser slide member will have become located at its operational position, ready for contact of the user's cheek with the riser slide member.

In view of the foregoing it is evident that the present invention is one well adapted to attain all of the objects and features hereinabove set forth, together with other objects and features which are inherent in the apparatus disclosed herein.

As will be readily apparent to those skilled in the art, the present invention may easily be produced in other specific forms without departing from its spirit or essential characteristics. The present embodiment is, therefore, to be considered as merely illustrative and not restrictive, the scope of the invention being indicated by the claims rather than the foregoing description, and all changes which come within the meaning and range of equivalence of the claims are therefore intended to be embraced therein. 

I claim:
 1. A cheek riser mechanism for attachment to a gun-stock of a firearm having a receiver and a having a movable cartridge charging handle, comprising: a cheek riser base member for substantially immoveable mounting to a gun-stock and defining a guide member; a movable cheek riser member being movably mounted to said cheek riser base member and being guided during movement by said guide member; and an urging member maintaining said movable cheek riser member at a predetermined use position and being yieldable responsive to application of force to said movable riser member to permit movement of said movable cheek riser member relative to said cheek riser base member and upon removal of said force returning said movable cheek riser to said predetermined use position.
 2. The cheek riser mechanism of claim 1, comprising: said guide member of said cheek riser base member being a guide rail defined by said cheek riser base member; and said movable cheek riser member having a guide groove receiving said guide rail in guided relation therein and guiding movement of said movable cheek riser member relative to said cheek riser base member.
 3. The cheek riser mechanism of claim 1, comprising: said guide member being a plurality of elongate guide rails projecting from said cheek riser base member and being disposed in substantially parallel relation with one another; and said movable riser member having a plurality of generally parallel elongate rail receiving grooves receiving said elongate guide rails in linear guided relation therein.
 4. The cheek riser mechanism of claim 1, comprising: said cheek riser base member defining an external surface and an internal surface; a guide and stop member projecting from said external surface of said cheek riser base member; and a guide groove located at said internal surface of said movable cheek riser member and having guiding engagement with said guide and stop member.
 5. The cheek riser mechanism of claim 1, comprising: a pair of spaced cheek riser guide members projecting forwardly from said cheek riser base member; elongate guide rail members projecting from each of said spaced cheek riser guide members and being disposed in substantially parallel relation with one another; and said movable cheek riser member having a forward wall structure defining spaced guide slots each receiving one of said elongate guide rail members in guided engagement therein.
 6. The cheek riser mechanism of claim 1, comprising: said urging member being a spring retainer structure being defined within said cheek riser base member; a spring passage being defined within said spring retainer structure; and a helical compression spring and spring plunger being at least partially located within said spring passage, said spring plunger having an end portion thereof disposed in fixed relation with said movable cheek riser member.
 7. The cheek riser mechanism of claim 6, comprising: said movable cheek riser member defining a front wall; and said spring plunger having a mounting plate in fixed relation therewith, said mounting plate being mounted in fixed relation with said front wall.
 8. The cheek riser mechanism of claim 1, comprising: said cheek riser base member being of generally U-shaped cross-sectional configuration and having a downwardly facing elongate recess within which the upper portion of a gun-stock is received; a plurality of mounting holes being defined by said cheek riser base member; and fasteners extending through said mounting holes and securing said cheek riser base member in fixed relation with the gun-stock; and said movable cheek riser member being secured in movable relation with said cheek riser base member and being urged forwardly to a predetermined operational position by said urging device and being movable rearwardly from said predetermined operational position by a force sufficient to overcome the resistance of said urging device.
 9. The cheek riser mechanism of claim 8, comprising: said cheek riser base member defining an external surface and an internal surface and said movable cheek riser member being of generally U-shaped cross section and defining external and internal surfaces; a pair of guide and stop members projecting from said external surface of said cheek riser base member; and a pair of elongate closed end guide grooves located at said internal surface of said movable cheek riser member and having guiding engagement with said guide and stop members; a plunger passage being defined in said cheek riser base member; a plunger member being mounted to said movable cheek riser member and having a portion thereof located within said plunger passage; said urging member being a helical spring surrounding said plunger and having a portion thereof located within said plunger passage, said helical spring yielding to permit rearward movement of said movable cheek riser member from said predetermined use position responsive to a force and moving said movable cheek riser member forwardly to said predetermined use position.
 10. The cheek riser mechanism of claim 1, comprising: a pair of spaced cheek riser guide members projecting forwardly from said riser base member and defining a pair of generally parallel elongate guide rails; and said second cheek riser member being of generally U-shaped configuration and having a forward wall defining a pair of internal elongate guide slots receiving said generally parallel elongate guide rails and guiding said movable cheek riser member during linear movement thereof in relation with said cheek riser base member between said predetermined use position and a retracted position.
 11. A cheek riser mechanism of adjustable length for attachment to a gun-stock of an AR15 type tactical firearm having a receiver and a having a charging handle that is moved linearly rearward during cartridge charging, comprising: a cheek riser base member of generally U-shaped cross-section defining a recess receiving an upper portion of a gun-stock therein and defining a plurality of fastener holes receiving fasteners mounting said cheek riser base member in substantially immoveable relation with the gun-stock; a pair of elongate guide rail members projecting from said cheek riser base member; a movable cheek riser member of U-shaped cross-section being movably mounted to said cheek riser base member and defining guide slots disposed in guided engagement with said elongate guide rail members to permit reciprocating movement of said movable cheek riser member between a predetermined use position and a retracted position; and an urging member maintaining said cheek riser member at said predetermined use position relative to said cheek riser base member and being movable from said predetermined use position toward said retracted position during rearward manual actuation of the charging handle of the firearm and preventing interference with normal rearward movement of the charging handle during cartridge charging cycling of the firearm, said urging member returning said movable cheek riser member to said predetermined use position when manual force being applied to the charging is released.
 12. The cheek riser mechanism of claim 11, comprising: said guide member of said first cheek riser member being an elongate guide rail projecting from said first cheek riser member; and said second cheek riser member having an elongate guide groove receiving said elongate guide rail in linear guided relation therein and guiding linear movement of said second cheek riser member relative to said first cheek riser member.
 13. The cheek riser mechanism of claim 12, comprising: said guide member being a plurality of elongate guide rails projecting from said cheek riser base member and being disposed in substantially parallel relation with one another; and said movable riser member having a plurality of rail receiving grooves receiving said elongate guide rails in linear guided relation therein.
 14. The cheek riser mechanism of claim 11, comprising: a spring retainer structure being defined within said cheek riser base member; a spring passage being defined within said spring retainer structure; and a helical compression spring and spring plunger being at least partially located within said spring passage, said spring plunger having an end portion thereof disposed in fixed relation with said movable cheek riser member.
 15. The cheek riser mechanism of claim 14, comprising: said movable cheek riser member defining a front wall; and said spring plunger having a mounting plate in fixed relation therewith, said mounting plate being mounted in fixed relation with said front wall.
 16. The cheek riser mechanism of claim 11, comprising: said cheek riser base member being of generally U-shaped cross-sectional configuration and having a downwardly facing elongate recess within which the upper portion of a gun-stock is received; and a plurality of mounting holes being defined by said first cheek riser member and receiving fasteners securing said first cheek riser member in fixed relation with the gun-stock.
 17. The cheek riser mechanism of claim 16, comprising: a plurality of internal structural rib members being defined within said cheek riser base member and being disposed for engagement with a gun-stock to which said cheek riser base member is mounted.
 18. The cheek riser mechanism of claim 11, comprising: a pair of spaced cheek riser guide members projecting forwardly from said cheek riser base member and define a pair of generally parallel elongate guide rails projecting from said generally U-shaped riser base member; said movable cheek riser member being of generally U-shaped configuration and having a front wall defining a pair of spaced guide slots within which said generally parallel elongate guide rails are received for guiding reciprocating movement of said front wall portion of said movable cheek riser member; said cheek riser base member defining guide and stop projections; and said pair of internal elongate guide grooves receiving said guide and stop projections in guided relation and guiding linear movement of said movable cheek riser member between a use position and a retracted position. 